Okay, my first post, and found these forums via the YouTube channel so, Howdy All!
I'm working on not so much what folks refer to as a diesel-hybrid but my own flavor, but more on that in a moment.
Yes, you can have a totally electric and solar sailboat/powerboat. WAFI, you mentioned following"Following Uma," I know them and the channel, but you need to do Jordan & Randi's "Learning the Lines." instead (you can keep with Uma, but Jordan has it going on). They take a 32-foot Endeavor, completely redo her, and go totally electric with an ElectricYacht 10kw motor, 12x 100ah Battleborn batteries set up in three 100ah banks for 300ah at 48VDC to drive the motor. Ships 12VDC and 120VAC are via inverter and charging is via 600 watts of solar. They did it for a year at anchor running power tools and occasionally a 5000 BTU A/C. You've got to watch your current use on a boat, period! I've lived on two for near a year each; it's a different lifestyle that teaches one to be frugal with everything, it's good for you. Jordan and Randi can sail along the Flordia coast; they're from Tampa I think, and down to the keys, but I would not go into the open ocean nor the Carribean. They don't have enough power to buck some of the currents that have been mentioned previously in this thread with a 10kw motor, a 20kw, maybe, but not me, and I'll get to why shortly.
It is possible to build a totally electric boat, catamaran, monohull sailboat, or powerboat that can sail the seven seas with dependability and safely if you have enough money and the right team of experts behind you, but for regular folks, even wealthy ones, the technology is just not there yet, it close though. The best solar panels are only 24.1% efficient, but they're cheap nowadays, so that makes them very practical for use in high wattage arrays. The motors are state of the art and can go to 40kw, which is equivalent to a 68hp diesel. The charging systems, inverters, etc. are fantastic and very reasonable, but it's still storage that's the issue. I'm looking at $11,400 for 12 batteries from Battleborn at $950 each, but those batteries can do 100% DOD plus they are good to 3000 to 5000 cycles if you don't go below 80% discharge too often. Think about this, 3000 cycles are over eight years with one cycle a day. The batteries have a 10-year warranty, and over their life, their cost per kWh is a fraction of anything else, including shore power. Lead-Acid are primitive by comparison and incredibly expensive when you do the long term numbers. The problem is the cost when you want to run things like A\C or compressors to refill dive tanks; even watermakers use a lot of current because of the high-pressure pump. Do a load analysis of everything you plan to run on your batteries, and that will tell you how much storage capacity you will need.
I just helped a friend of mine set up his Morgan 32 just like I'm doing for my soon to be Endeavor 37. He has 300ah as mentioned, and runs his 5000 BTU marine A\C pretty much all the time down here in summer and even during the winter at times. It's the Gulf Coast climate. The A\C uses 5amps at full load, but will not run full at capacity all the time, maybe a third once the small and well-insulated area is cold. It doesn't kick on that often if you're not going in and out the hatch. He has a watermaker. It does 1.5 gals per hour using ten amps, but you only run every other day or so to make up the water you've consumed. He has a marine washer\dryer combo (expensive!) that pull 12 amps on dry, but he runs it once a week. That's all of his significant current hogs. We set up 800 watts of solar in three places, and he has two wind turbines.
Now we are keeping our diesel. The DC motor mounts behind the diesel and above the shaft where it's belt driving the propeller shaft. You can use the diesel, the 48VDC 20kw motor, or both at the same time if, say, for instance, you hit one of those badass currents we're mentioned. You can also drive an alternator and a generator while propelling the boat and running both 12VDC and 120VAC systems, and charging when the sun doesn't shine enough, or doesn't shine at all, or you might need to run an air compressor for some reason like, oh I don't know, maybe filling dive tanks? Drive the air compressor with the diesel. A 20kw 48 VDC motor will drive my Endeavor 37 at its hull speed of just under 7 knots at half throttle and like that, in good sunlight, the solar panels are keeping up with the load or even charging to batteries somewhat. Now, I'd cross the Atlantic in that set up in a heartbeat. You have the diesel, you have the electric motor if one fails you have the other. You have all the comforts of home.
Now a catamaran is a bit more expensive. You will need two motors, one in each hull. You will need one diesel-powered generator that can run both motors if need be, and charge even more batteries (two motors), and a bigger electrical system, but it's basically the same setup. The bigger the boat, the bigger the A\C required to keep it cool hence more batteries and solar panels.
I just watched the video from 2018 of the comparison of the LiFePO4 against the Tesla battery and the Tesla would be the best by leaps and bounds in cost and ability, but can it be used in a marine application like I'm talking about here? That is my question. Below is the link to the video of the battery comparison for those of you interested in this Tesla battery.
Off-grid Solar Battery Price Comparison: Tesla vs. FLA vs. SLA vs. LiFePO4 vs. Tesla:
